# -*- coding:utf-8 -*-
'''
输入两个单调递增的链表，输出两个链表合成后的链表，当然我们需要合成后的链表满足单调不减规则。

递归法从尾指针比较
'''
class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None


class Solution:
    # 返回合并后列表
    def Merge(self, pHead1, pHead2):
        # write code here
        if pHead1 is None:
            return pHead2
        if pHead2 is None:
            return pHead1

        if pHead1.val <= pHead2.val:
            pHead1.next = self.Merge(pHead1.next, pHead2)
            return pHead1
        else:
            pHead2.next = self.Merge(pHead1, pHead2.next)
            return pHead2

